1. Field of the Invention
The present invention pertains to the process of making energetic materials, more particularly to a continuous process for making co-layered energetic materials, and most particularly to a continuous process for making co-layered energetic materials using multiple twin-screw extruders.
2. Description of the Related Art
For many years, it has been known that combining separate layers of different energetic materials produces a final energetic product that generates increased performance for certain uses. The current method of making co-layered or multi-layered energetic materials requires numerous processing steps.
First, different energetic formulations are mixed and extruded into ribbons. This extrusion can be accomplished using numerous methods disclosed within the prior art. The individual ribbons are then rolled to a desired thickness. These multiple ribbons are then rolled into a multi-layered ribbon. The multi-layered ribbon is finally cut into the final desired shapes. Their are many problems and limitations associated with this method. Due to the number of steps, the labor involved in each step, and the multiple pieces of equipment necessary for the number of steps, the manufacturing costs for the current process are quite high. Also, due to the number of processing steps that require personnel handling of the energetic material, the safety risks are great associated with the above described processing technique. Finally, due to the large number of cutting and trimming operations involved in the process, high amounts of waste material result.
One particular method has been developed to improve safety by reduction of handling for energetic material manufacture. U.S. Pat. No. 5,565,150 discloses a process of continuous mixing of energetic materials in a twin-screw extruder, followed by granulating and drying. The patent discloses a process of mixing energetic materials within the twin-screw extruder and having the twin-screws bulk granulate the material in order to obtain energetic granules used for gun propellants and other uses. This process reduces personnel handling of material resulting in a significant safety reduction. However, this process results in granules of energetic materials of one particular formulation and not ribbons of energetic materials of differing formulations.
Therefore, it is desired to provide a method of producing co or multi-layered energetic materials using multiple twin-screw extruders in order to reduce manufacturing costs and increase safety.